Function contract::payment::direct_pay

#[no_mangle]
pub extern "C" fn direct_pay()

Direct buy is used to proxy the casper transfers through droplinked’s contract, to transfer droplinked’s share to its account, and transfer the rest of it to the producer

fee% of the product price should go to droplinked’s account, and the rest of it (tax price + shipping price + rest of the product price) to the producer’s account